Ball valve electromagnetic fuel injector

ABSTRACT

A ball valve electromagnetic fuel injector includes a spring biased low-mass magnetic ball which oscillates with respect to a conical valve seat in the injector case to open and close the fuel supply. A solenoid having a stationary pole piece with a spherical tip recess provides a uniform attractive force in pulling the ball away from the valve seat to the open position in accordance with a fuel metering schedule.

United States Patent 7 1 1 [11] 3,731,880 Williams [4 1 May 8, 1973 BALLVALVE ELECTROMAGNETIC 3,628,767 12/1971 Lombard ..251 141 x FUELINJECTOR [75] Inventor: Donald L. Williams, Port Clinton, PrimaryExaminer-Allen Knowles ()hi Assistant Examiner-Michael Y. Mar [73]Assignee: General Motors Corporation, Attorney-J Carpenter et Detroit,Mlch. ABSTRACT 22 Filed: Oct. 8, 1971 A ball valve electromagnetlc fuelin ector mcludes a PP 187,623 spring biased low-mass magneticball whichoscillates with respect to a conical valve seat in the injector case 52us. 01 ..239/585, 251/141 to p and Close the fuel pp y- A solenoidhaving a [51] Int. Cl ..'.F16k 31/06 stationary pole piece with aspherical tip recess pro- [58] Field oiSearch ..239/584, 585, 586; videsa uniform attractive force in pulling the ball 158/28; 261/76; 251/129,141 away from the valve seat to the open position in accordance with afuel metering schedule. [56] References Cited 2 Claims, 1 Drawing FigureUNITED STATES PATENTS 3,245,652 4/1966 Roth .25l/141 X BALL VALVEELECTROMAGNETIC FUEL INJECTOR The present invention relates to fuelinjectors and, in particular, to injector valves for electromagneticfuel injectors used in internal combustion engines.

Fuel injection systems typically incorporate a plurality of fuelinjectors, usually one for each cylinder of the engine, which functionto meter precisely controlled quantities of atomized fuel to the engine.Generally, these injectors are positioned so as to inject the fuel in aproperly timed sequence into. the intake manifold upstream of the intakevalve associated with the cylinder.

Such injectors oftentimes employ an electromagnetically actuated valveelement which serves to open and close the fuel path to the injectornozzle. A typical construction uses an electromagnetically actuatedmoving part or dynamic mass which, in its external configuration,embodies a valve element that opens and closes against a valve seat. Thetip of the moving part incorporates a pintle or nozzle element whichestablishes an annular orifice-downstream of the valve and serves toatomize the pulsing fuel as it emerges from the nozzle orifice. Thevalve element is provided with only one degree of freedom, axialreciprocation and, to provide proper functioning, the valve element musthave. surfaces which precisely mate with their associated parts.Thus,.the roundness and concentricity of the valve element with respectto. the valve seat must be precisely controlled to ensure completeclosing of the valve. Similar requirements must apply totherelationships between the pintle and the orifice if completeatomization of the fuel is to be achieved.

The above relationships are also difficult to maintain in service. Forinstance, thelarge mass of the valve element results in high impactforces with the valve seat The present invention overcomes theaforementioned difficulties by providing an electromagnetically operatedvalve for a fuel injector that incorporates a low-mass valve elementhaving an inherently precise seating with the valve seat and an improvedresponse time. More particularly, the injector includes a valve caseincluding a nozzle having a conical valve seat terminating with acircular axial orifice. A precision lowmass magnetizable spherical ballis axially guided by the case relative to the valve seat. A helicalcoiled spring biases the ball to a normally closed position. A solenoidin the case includes a stationary pole piece having a tip provided witha spherical recess in which the ball seats. The recess establishes auniform gap with the outer surface of the ball to provide a uniformmagnetic force for attracting the latter uponenergization of thesolenoid coil. The pole piee is axially adjustable relative to the ballto provide a value response time in accordance with the desired fuelschedule. The spherical shape of the ball and the conical shape of thevalve seat can be precisely controlled thereby imposing less demandingproduction requirements than in the aforementioned construction. Theball and the valve seat are inherently self-centering and provide addeddegrees of freedom in positioning the ball with respect to the valveseat and the pole piece. Additionally, the dynamic mass is minimizedthereby providing an injector having a faster response time and improvedfuel metering accuracy. In operation, fuel flows through throughtangential slots in the nozzle upstream of the valve. The slots impart aswirl motion that directly atomizes the fuel at the nozzle tip andeliminates the need for a valve element and a pintle at a locationexternal of the injector.

The above and other features of the present invention will be apparentto one skilled in the art upon reading the following detaileddescription, reference being made to the accompanying drawingillustrating a preferred embodiment wherein the single F IGURE is across sectional view of a ball valve electromagnetic fuel injector madein accordance with the present-invention.

Referring to the drawing, a fuel injector 10 is i mounted within astepped bore in the intake manifold 12 of an internal combustionengine..The bore comprises an upper section 14, a middle section 16, anda lower section 18, the latter of which terminates at the inductionpassage 20 of the intakemanifold 12. Fuel is fed to the injector 10through a port 22 which communicates with the middle section 16. Theinjector 10 is controlled in a conventional manner to meter fuelentering through the port 22 and to inject precise quantities ofatomized fuel to the manifold 12.

The injector generally comprise an injector case 30, a solenoid 32, anozzle 34, a ball 36, and an electrical contact assembly 37.

The case 30 is generally designed to permit direct unoriented insertioninto the bore and comprises an enlarged body 40 terminating at its lowerend in a lower section or nose 42 of reduced diameter. The body 40 isreceived in the upper section 14 and the nose 42 is received in thesections 16 and 18. The nose 42 defines with the section 16 an annularfluid chamber 44. The outer surface of the body 40 includes a pair ofaxially spaced annular grooves, each of which contains an 0- ring 46.The O-rings 46 effect a seal between the case 30 and the upper section14 of the bore. The nose 42 includes an annular groove retaining anO-ring 48 which provides a seal at the lower section 18 of the bore.

The configuration of the case 30 is suitably shaped and proportioned soas to be easily fabricated by cold extrusions. The oriented grain flowinherent in the extrusion process provides an improved magneticpermeability for the casing. Preferably, the case 30 is formed of a lowcarbon steel or a 3 to 4 percent silicon transformer steel.

The case 30 is additionally provided with an upwardly opening cavity 50housing the solenoid 32. The cavity 50 includes a conical lower portion52 terminating with an annular flux guide 54 having a circular openingfor guiding the axial oscillating movement of the ball 36.

The nose 42 of the case 30 is provided with a downwardly opening cavity60. A plurality of radial ports 62 formed in the nose 42 exteriorallycommu' nicate with the chamber 44 and interiorally communicate with thecavity 60. An annular fuel filter 66 formed of a porous, sintered bronzeperipherally. surrounds the ports 62. The filter 66 is pressed fittedover the nose 42 and serves to filter contaminants from the enteringfuel. 34.cc

The nozzle 34 is generally cylindrical and may be injection molded of asuitable plastic material such as polyacetal plastic. The nozzle 34 isinserted in the cavity 60 and the end rim 67 of the nose 42 is spuninwardly to retain the nozzle 34 therein. The upper section of thenozzle 34 has a reduced diameter and defines with the inner surface ofthe cavity 60 an annular fuel chamber 68. The upper face of the nozzle34 includes a plurality of radially extending slots 70 and a centralconical valve seat 72. If desired, the slots 70 may be tangentiallyoriented with respect to the valve seat 72 to impart a circumferentialswirling motion to the entering fuel. The apex of the valve seat 72communicates with a circular axial orifice 74 which discharges at thetip 76 of thenozzle 34.

The ball 36 is formed ofa magnetizable steel and has a highly finishedexterior which is inherently. round and provides a positive seal withthe valve seat 72.

The solenoid 32 comprises a coil bobbin 80 supporting a coil 82, and apole piece 84 adjustably carried on a base plate 85. The coil bobbin 80is housed within the cavity 50 and includes a lower section 86 whichengages the case.30 to axially position the solenoid 32. The pole piece84 is coaxially located with respect to the orifice 74 in a central boreon the bobbin 80. An ring 88 provides a seal between the bobbin 80 andthe case 30. The upper section of the coil bobbin 80 includes twoupwardly extending slotted studs 90 which project through apertures inthe base plate 85. The coil 82 includes lead wires 92 and 94 that extendupwardly through the slots in the studs 90. The upper rim 96 of the case30 is spun over the base plate 85 to lock the solenoid 32 in place.

The contact assembly 37 comprises a circular contact plate 100, anannular contact ring 102, and a cupshaped grounding ring 104. Thecontact plate 100 is formed of a nonconductive material and includes acentral aperture and diametrically opposed apertures which register withthe studs 90. The grounding ring 104 surrounds the case 30 and isattached to the outer periphery of the plate 100 at tangs 106. Thecontact ring 102 has a lower end embedded in the contact plate 100 andan upper end terminating at a circular rim 108.-

The contact assembly 37 is positioned on the rim 96 and located thereonby the studs 90. The lead wire 92 is welded to the contact ring 102. Thelead wire 94 is welded to the grounding ring 104.

The pole piece 84 includes a threaded end 110 which is adjustablythreaded trough the base plate 85. Thelower end or tip 111 of the polepiece 84 is provided with a spherical recess 112 that conforms to theshape of the ball 36. A helically coiled spring 114 interposed betweenthe ball 36 and the coil bobbin 80 normally biases the ball 36 into theseating relationship with the valve seat 72. The spherical surface ofthe recess 112 in cooperation with the outer surface of the ball 36provides uniform magnetic field for attracting the ball. The pole piece84 is axially adjustable with respect to the ball 36 and valve seat 72to provide the desired response time between the open and closedpositions. Following flow setting of the valve assegbly, the contactassembly 37 and the case 30 are encapsulated by an injection molded endcap 120 which serves to seal the interior of the case 30, permanentlysecure the rings 102, 104, and provide an anti-rotation lock for thepole piece 84. By means ofa suitable connector and hold down devicewhich engages the lower surface fthe grounding ring 102 and top surfaceof the rim 108 for holding the injector 10 in position on the manifold2, the injector 10 is connected in a conventional circuit for energizingthe solenoid 32 in accordance with a predetermined schedule.

In operation, the ball 36 is normally biased to the closed position intothe seating engagement with the valve seat 72 by the spring 114 and thehydraulic fuel pressure in cavity 50. This closes the fuel path betweenthe fluid chamber 44, the ports 62, the interior passage defined by thechamber 68 and the slots 70, and the orifice 74. Upon receiving anelectrical impulse from the control unit, the coil .82 of the solenoid32 is energized thereby magnetizing the pole piece 84 and applying auniform attractive force to the ball 36 sufficient to overcome the forcedeveloped by the pressure of the fuel plus the biasing force of thespring 114. This causes the ball 36 to shift upwardly against the polepiece 84 in seating engagement in the recess 112 and opens the valvethus allowing the fuel to flow through the port 22, the chamber 44, theports 62, the slots 70, and the orifice 74.-The fuel emerges at the tip76 in a finely atomized form and continues as long as the solenoid 32 isenergized. Upon termination of the electrical impulse, the coil 82 isdeenergized causing the magnetic field to collapse and the spring andthe hydraulic forces cause the ball 36 to seat against the valve seat 72thereby shutting off the flow of fuel until the next electrical impulse.

Although only one form of this invention has been shown and described,other forms will be readily apparent to those skilled in the art.Therefore, it is not intended to limit the scope of this invention bythe embodiment selected for the purpose of this disclosure but only bythe claims which follow.

.What is claimed is:

1. An electromagnetic fuel injector comprising: an injector case havinga fuel inlet; a nozzle carried by said case and having an axial fueloutlet; passage means between said inlet and said outlet defining a fuelpath through said case; a conical valve seat in said passage meanscommunicating with said outlet; a spherical magnetizable ball supportedin said case for oscillation between a first position seated againstsaid valve seat for closing said fuel path and a second position remotefrom said valve seat for opening said fuel path; spring means betweensaid ball and said case for biasing said ball to said first position; asolenoid in said case including a stationary magnetizable pole piecehaving a spherical recess at one end thereof spaced from said valveseat, said ball seating in said recess in said second position andmaintaining a constant gap with said recess in said first positionwhereby said pole piece applies a uniform attractive force to said ballwhen said solenoid is energized to shift said ball to said secondposition against the biasing force of the spring means thereby openingsaid fuel path.

2. A ball valve electromagnetic fuel injector comprisingz-an injectorcase; a fuel inlet port in said case; a nozzle mounted on one end ofsaid case; a circular axial orifice formed in said nozzle; a conicalvalve seat formed in said nozzle coaxial with said orifice; a passage insaid case fluidly connecting said inlet port one end of said pole piecespaced! from said valve seat and adapted to seat said ball in said openposition, said recess maintaining a constant gap with said ball forapplying a uniform attractive force to whereby magnetizing said polepiece applies said uniform attractive force to said ball to shift thelatter to the closed position to said recess against the biasing forceof the spring thereby opening a fuel path through said injector.

1. An electromagnetic fuel injector comprising: an injector case havinga fuel inlet; a nozzle carried by said case and having an axial fueloutlet; passage means between said inlet and said outlet defining a fuelpath through said case; a conical valve seat in said passage meanscommunicating with said outlet; a spherical magnetizable ball supportedin said case for oscillation between a first position seated againstsaid valve seat for closing said fuel path and a second position remotefrom said valve seat for opening said fuel path; spring means betweensaid ball and said case for biasing said ball to said first position; asolenoid in said case including a stationary magnetizable pole piecehaving a spherical recess at one end thereof spaced from said valveseat, said ball seating in said recess in said second position andmaintaining a constant gap with said recess in said first positionwhereby said pole piece applies a uniform attractive force to said ballwhen said solenoid is energized to shift said ball to said secondposition against the biasing force of the spring means thereby openingsaid fuel path.
 2. A ball valve electromagnetic fuel injectorcomprising: an injector case; a fuel inlet port in said case; a nozzlemounted on one end of said case; a circular axial orifice formed in saidnozzle; a conical valve seat formed in said nozzle coaxial with saidorifice; a passage in said case fluidly connecting said inlet port andsaid orifice; an annular guide member on said case aligned with theorifice and the valve seat; a low mass spherical magnetizable ball insaid case restrained by said guide member for axial movement between aclosed position against said valve seat and an open position remote fromsaid valve seat; a spring engaging said ball and said case for biasingsaid ball to said closed position; a solenoid mounted at the other endof said case; a stationary magnetizable pole piece on said solenoidcoaxial with said valve seat; a spherical recess at one end of said polepiece spaced from said valve seat and adapted to seat said ball in saidopen position, said recess maintaining a constant gap with said ball forapplying a uniform attractive force to whereby magnetizing said polepiece applies said uniform attractive force to said ball to shift thelatter to the closed position to said recess against the biasing forceof the spring thereby opening a fuel path through said injector.